The present invention relates to an obturator disc for an optical transducer of known type, for example, of the type described in the U.S. patent application Ser. No. 678,994 filed on Dec. 6, 1984 and assigned to the same assignee of the present invention. The obturator disc according to the invention comprises a cylindrical element of transparent material provided with a central hub for fitting the disc on to a rotating member, and a layer of opaque material on a front surface of the cylindrical element and provided with a plurality of transparent windows disposed radially along an annular zone coaxial with the central hub.
An obturator disc is known wherein the cylindrical element is of glass and the layer of opaque material is constituted by a thin film on a surface of the glass. In this disc, the central hub is formed by a pair of metal flanges which are connected to the cylindrical element. This obturator disc, however, proves to be costly and requires accurate centering between the hub and the glass element so that the windows in the film may be perfectly coaxial with the axis of the hub.